Before describing the dynamic planning method and system, some introductory concepts and terminology are explained. As used herein, the term “project planning method” is used to refer to a process followed to determine a project plan. The term “project planning model” as used herein, refers to a particular representation of the project planning method. Examples below of an activity pre-structured process model and of a relationship pre-structure model, associated with FIGS. 6 and 7, are illustrative examples of project planning models. The term “project planning tool” as used herein, refers to a mechanism, for example a computer program, that applies a project planning method to a project planning model.
A project planning model is a model that can be used to plan a project (e.g. a construction project). Some well-known project planning models include a dependency structure matrix (DSM), a critical path method (CPM), a precedence diagram method (PDM), a concurrent engineering technique, a critical chain technique, an overlapping framework technique, various system dynamics techniques, a simulation language for alternative modeling technique (SLAM), a graphical evaluation and review technique (GERT), a queue graphical evaluation and review technique (Q-GERT), and a program evaluation and review technique (PERT). Such conventional project planning models are thus used to plan and control projects.
Of the above methods, CPM, PDM, PERT, and GERT will be recognized to be the most common network based project planning models. A network based project planning model provides a model of a project plan having activities and time relationship linkages between the activities. The project plan database underlying the conventional project planning model will be referred to herein as conventional project plan data, having conventional project plan data elements.
In general, the term “upstream” activity will be used herein to describe an activity whose progress and work quality influence the progress and/or work quality of related succeeding activities. The upstream activity can often begin at an earlier time than the related succeeding activities. The term “downstream” activity will be used to describe the succeeding activity whose progress and work quality are influenced by the progress and/or work quality of a related upstream activity. The downstream activity can often begin at a later time than the related upstream activity. Thus, considering only two related activities of a project plan that do not occur at the same time, one is an upstream activity and one is a downstream activity.
The PDM conventional project plan data elements include a list of activities, an activity duration value for each activity, and time precedence relationships between the activities. Time precedence relationships include finish to start (FS), finish to finish (FF), start to finish (SF), and start to start (SS). An FS time precedence relationship is one for which a downstream activity is planned to start immediately upon the finish of an upstream activity. An FF time precedence relationship is one for which a two activities are planned to finish at the same time. An SF time precedence relationship is one for which a downstream activity is planned to start immediately upon the finish of an upstream activity. An SS time precedence relationship is one for which two activities are planned to start at the same time. The FS and the SF time precedence relationships are similarly described in terms of upstream and downstream activities. It will be recognized that their difference arises only in the physical sequence by which the two activities are represented on a chart, i.e. whether the downstream activity is represented above or below the upstream activity.
The time precedence relationships also can include lead or lag times. For example, when two activities are related in a FS time precedence relationship with no lead or lag, a downstream activity is planned to start at the completion of an upstream activity to which it is related. For another example, when two activities are time related in an FS relationship with lead, a downstream activity can begin a lead period before the completion of an upstream activity to which it is related. This is contrasted with an FS relationship with lag for which the downstream activity is delayed to start with a lag delay after the completion of an upstream activity to which it is related.
Contingency time buffers, also called contingency buffers, are conventionally applied to the end of one or more activities in the project plan to absorb the effect of time delay, or slippage, of individual activities. Contingency buffers attempt to ensure that the total time duration of the project is preserved even when the durations of individual activities expand, either from expected or from unexpected changes.
However, conventional contingency buffers are often inefficient. Once added to the duration of an activity, a contingency buffer can be considered by those workers performing the activity to be part of the original time schedule of the activity without distinction. When workers realize that they have extra time to complete a task, their work tends to expand to fill the perceived extra time. As a result, the contingency buffer generally does not function effectively to protect the initially planned overall schedule duration.
To the conventional project plan data elements above, PERT and GERT include various other conventional project plan data element. PERT includes probability values associated with the duration value of each activity. The probability value assigns a probability to the likelihood that an activity will be completed within its scheduled duration. PERT also adds a path probability value to each time precedence relationship. The path probability value corresponds to the likelihood that a time precedence relationship will be achieved as planned. GERT adds probabilistic time precedence relationship branching.
A project planning method provides the ability to update the project plan at any time. For an update of the project plan, the user enters new or additional project plan data into the project planning method. Conventional project planning methods use a static approach for updating the project plan. Generally, all time precedence relationships generated when the project is initially planned remain unchanged when the plan is updated. Also, only those one or more activities for which new project planning data has been obtained are updated. No update occurs for activities that are the same, or similar to, those one or more activities, even though such an update would be applicable.
Therefore, it would be desirable to provide a project planning model that has the ability to absorb time slippages and project changes yet does not tend to expand a project schedule when such slippages and changes occur. It would be further desirable to provide an approach for updating the project plan that can both alter the time precedence relationships between activities based upon updated project plan data and can identify and update activities that are the same as or similar to those for which new project plan data has been obtained.